Wilting fan leaves problem!?

Hey guys, i have 3 plants (all about 1.4 months old) 1 week into flowering under 150w HPS. 2 plants are fine.. but the other (white widow) has all of its fan leaves apart from the uppermost 2 drooping down to the ground. Only the fan leavs not the leaves on the branches where u take clones from though. Just the big huge fan leaves... I don't know why this is happening can anyone help me? I water only when the plants need it.. probably once a week when the soil dries up and i cant feel any moisture a finger in the pot. The pots are big enough for the plant size. And i don't use any Nutes, so it can't be down to that.. im sorry i cant take a picture because i have no camera.. any help would greatly be appriciated.. its a lovely looking plant just dont want it to die (its female too!!) anyways, thanks.

Happy Growing!

how far is the Hps from the plants? could be burning em up!! try movin it further away say 12" - 15" away from the tops..also now is a gd time to start nuteing its very pos that those baby are not going as gd due to lack/none things it can munch on!!(lamens terms) so give em a gd nutein with some orchid bloom, or any kind of blooming material you can get from the local GC...

the light is not to close to the plants at all, its not burning them.. I will purchase some orchid bloom this weekend and give them a good feed, thanks for the advice!

Water once a week ,,,how,,,,About two days are all i can go between water,,,each plant is differant on its needs,if you try to do all of them the same you will have problems,,I water as soon as the surface GETS DRY,,,stick your finger in to 1/2inch,if no soil sticks to your finger water,,,never let them dry all the way out,causes stress...